Method and system for fabricating an electrooptical device

ABSTRACT

Techniques for successively fabricating liquid crystal cells at low cost, using two resinous substrates wound on their respective rolls. A color filter and an electrode pattern are formed by printing techniques. Furthermore, an orientation film is printed. These manufacturing steps are carried out successively by rotating various rolls.

This application is a divisional of application Ser. No. 08/566,143,filed Dec. 1, 1995, now U.S. Pat. No. 5,929,161.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of fabricating liquid-crystalelectrooptical devices using flexible film substrates and also to asystem for fabricating such liquid-crystal electrooptical devices usingflexible film substrates.

2. Description of the Related Art

A liquid-crystal electrooptical device is known as a thin, small-sized,lightweight display device. The liquid-crystal electrooptical devicecomprises a pair of substrates spaced several micrometers from eachother and a liquid crystal material held between the substrates. Thesubstrates are required to transmit visible light and so glasssubstrates are generally used as the substrates. The glass substrateshave the required optical characteristics. In addition, they areinexpensive.

The liquid-crystal electrooptical device must meet the followingtechnical requirements: (1) It is small in size and lightweight; and (2)the cost of fabricating the liquid-crystal electrooptical device isreduced and its productivity is improved.

Of these requirements, the requirement (1) is that the liquid-crystalelectrooptical device is made thinner and lighter in weight. A knownconfiguration which satisfies these requirements uses resinoussubstrates (generally known also as plastic substrates) transmittinglight.

Where resinous substrates are employed, reductions in size and weightcan be accomplished. Since the substrates themselves have flexibility, aphysical stress can be applied to them, or they can be used in a curvedstate. These kinds of usage can further extend the application of theliquid-crystal electro-optical device.

However, where resinous substrates are used, a reduction in fabricationcost and an improvement in the productivity are not accomplished.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide techniques forfabricating liquid-crystal electrooptical devices, using flexiblesubstrates, at low cost and with high productivity.

A system for fabricating liquid crystal cells according to the presentinvention comprises a first roll on which a first flexible substrate hasbeen wound, a second roll on which a second flexible substrate has beenwound, means for forming a liquid crystal material layer on the surfaceof the first substrate, and means for bonding together the first andsecond substrates 206,201.

A specific example of the structure of the above-describe ed system isshown in FIG. 1, where a first flexible substrate 206 has been wound ona first roll 119. A second flexible substrate 201 has been wound on asecond roll 101. A dripping device 135 acts to drip a liquid crystalmaterial onto the surface of the first substrate 206. A set of rolls,137 and 138, is the means for bonding together the first and secondsubstrates 206,201.

The flexible substrates can be made from PET (polyethyleneterephthalate), PEN (polyethylene naphthalate), PES (poly-ethylenesulfite), polyimide, or PAR (polyarylate).

A method of fabricating liquid crystal cells according to the presentinvention consists of preparing a first flexible substrate wound on afirst roll, preparing a second flexible substrate wound on a secondroll, and squeezing a liquid crystal material between the first andsecond substrates to form an elongated liquid crystal cell.

Another method of fabricating liquid crystal cells according to thepresent invention consists of winding a flexible substrate on a roll,printing an orientation film on the substrate, orienting molecules ofthe orientation film, spraying spacers on the orientation film, andprinting a sealing material. These manufacturing steps are effectedsuccessively.

A specific example of the above-described method is illustrated in FIG.1. An orientation film 209 is formed on the flexible substrate 206 byrolls 127 and 128, the substrate 206 being wound on the roll 119.Spacers 211 are sprayed. A sealing material (not shown) is printed.

Other objects and features of the invention will appear in the course ofthe description thereof, which follows.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic diagram of a system for fabricating liquid-crystalelectrooptical devices according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present example is a production system capable of producingliquid-crystal electrooptical devices in succession, each electroopticaldevice using flexible resinous substrates. This fabrication system isschematically shown in FIG. 1 and intended to produce the flexibleresinous substrates wound on rolls 101 and 119, for constructing eachliquid-crystal electrooptical device.

First, a manufacturing step regarding resinous substrates wound aroundthe roll 119 is described. In this example, resinous substrate coiledaround the roll 119 consist of film of PET (polyethylene terephthalate).A three-colored (R, G, and B) filter 203 is printed on the surface ofthe RET film 200 drawn out of the roll 112. This PET film acts as a basein forming the color filter 203. The color filter 203 is formed by meansof three sets of rolls 113. Where the manufactured liquid crystaldisplay is a monochrome display, these three sets of rolls are notnecessary.

After forming the color filter 203, a protective film 205 wound on aroll 115 is formed so as to cover the color filter 203 previouslyformed. A self-adhesive film 204 wound on a roll 116 is stuck on therear side of the base, i.e., on the opposite side of the surface onwhich the colored filter is formed. This series of manufacturing stepsis performed, using a pair of pressure rolls, 117 and 118.

Then, another PET film 206 which is wound on the roll 119 and forms abase is stuck via the self-adhesive film 204 by means of a set ofpressure rolls, 120 and 121. Subsequently, the protective film 205 ispeeled off by a roll 123 and wound on a roll 122.

Thereafter, an overcoat film 207 is printed by a set of rolls, 123 and124, to flatten the irregularities created by the formation of the colorfilter 203. This overcoat film 207 is made from a resinous materialtransparent to light.

A required electrode pattern 208 is printed, using a set of rolls, 125and 126. The electrode pattern 208 is made from a conductive ink.

Then, an orientation film 209 is printed by the use of a set of rolls,127 and 128. The orientation film 209 is passed through a heatingfurnace 129 to bake it. As a result, a solidified orientation film 210is obtained.

The orientation film 210 is passed between rolls 130 and 131 to rub thesurfaces of the orientation film 210. In this way, the molecules of thefilm are oriented. Then, spacers are sprayed from a spacer dispenser 132to place the spacers 211 on the oriented film 210.

Thereafter, a sealing material (not shown) is printed to bond togetheropposite substrates and to prevent the liquid crystal material fromleaking from the spacing between the substrates.

Subsequently, the liquid crystal material is dripped, using the liquidcrystal material-dripping device 135, to form a liquid crystal materiallayer 212. In this manner, one substrate is completed. The manufacturingsteps described thus far are successively carried out by rotating thevarious rolls.

The other substrate is manufactured in the manner described below. Adesired electrode pattern 213 is formed on the PET film 201 drawn out ofthe roll 101 by a pair of rolls 102 and 103. Then, an orientation film214 is printed through the use of a pair of rolls 104 and 105. The filmis baked by a heating furnace 108, so that a solidified orientation film215 is formed. Thereafter, the substrate is passed between a pair ofrolls 109 and 110 and guided to the rolls 137 and 138 to form a cell.

The liquid crystal cell is formed on the PET film pair by the stepsdescribed thus far. This PET film pair is passed between a pair of rolls137 and 138 to bond together the films, using a sealing material. Then,

Then, heating is done within a heating furnace 139 to cure the sealingmaterial, thus completing bonding of the substrates. The resultingsubstrate assembly is cut into desired size with a cutter 150. In thisway, a liquid crystal cell is completed.

The manufacturing steps described thus far are performed in successionby rotating the various rolls. By cutting the substrate assembly withthe cutter 150, liquid crystal cells are successively fabricated.

In the present example, passive liquid crystal cells are manufactured.It is also possible to fabricate active liquid crystal cells byfabricating nonlinear devices and TFTs simultaneously by printingtechniques.

In the present example, liquid crystal cells are formed on PET filmswhich are industrially often used like magnetic tape. Besides PET, PEN(polyethylene naphthalate), PES (polyethylene sulfite), polyimide, andPAR (polyarylate) can be used.

Where PET or PES film is used, birefringence may take place, in whichcase the image displayed on the device may be adversely affected. On theother hand, neither PES film nor PAR film induces birefringence and theysatisfy the optical characteristics which every display device mustmeet.

In the present invention, when flexible liquid crystal cells aremanufactured, flexible substrates wound on rolls are used. Consequently,liquid crystal cells can be manufactured in succession.

What is claimed is:
 1. A method for fabricating a display devicecomprising steps of: drawing a base film out of a roll around which abase film is wound; forming color filters on a front surface of saidbase film; drawing a first substrate out of a roll around which saidfirst substrate is wound; sticking said first substrate on a rearsurface of said base film having said color filters thereon; formingfirst electrode patterns to over said first substrate; drawing a secondsubstrate out of a roll around which said second substrate is wound;sticking said second substrate over said first substrate to form asubstrate assembly; and cutting said substrate assembly into a pluralityof cells.
 2. A method according to claim 1 further comprising a step offorming an overcoat film over said color filters.
 3. A method accordingto claim 2 wherein said overcoat film comprises transparent resin.
 4. Amethod according to claim 2, wherein said overcoat film has a flattenedsurface.
 5. A method according to claim 1 further comprising steps of:forming a first orientation film over said first electrode patterns;heating said first orientation film; and rubbing a surface of saidheated first orientation film.
 6. A method according to claim 1 furthercomprising at least a step of forming a sealing material over said firstsubstrate.
 7. A method according to claim 1 further comprising steps of:forming second electrode patterns over said second substrate; forming asecond orientation film over said second electrode patterns; and heatingsaid second orientation film.
 8. A method according to claim 1, whereinsaid base film comprises polyethylene terephthalate.
 9. A methodaccording to claim 1, wherein said first and second substrates comprisea material selected from the group consisting of polyethyleneterephthalate, polyethylene naphalate, polyethylene sulfite, polyimide,and polyarylate.
 10. A method according to claim 1, wherein said displaydevice is selected from a passive matrix type display device and anactive matrix type display device.
 11. A method for fabricating displaydevice comprising steps of: drawing a base film out of a roll aroundwhich a base film is wound; forming color filters on a front surface ofsaid base film; drawing a first substrate out of a roll around whichsaid first substrate is wound; sticking said first substrate on a rearsurface of said base film having said color filters thereon; forming anovercoat film over said color filters and said first substrate; formingfirst electrode patterns to over said overcoat film; drawing a secondsubstrate out of a roll around which said second substrate is wound;sticking said second substrate over said first substrate to form asubstrate assembly; and cutting said substrate assembly into a pluralityof cells.
 12. A method according to claim 11 wherein said overcoat filmcomprises transparent resin.
 13. A method according to claim 11 furthercomprising steps of: forming a first orientation film over said firstelectrodes pattern; heating said first orientation film; and rubbing asurface of said heated first orientation film.
 14. A method according toclaim 11 further comprising at least a step of forming a scalingmaterial over said first substrate.
 15. A method according to claim 11further comprising steps of: forming second electrode patterns over saidsecond substrate; forming a second orientation film over said secondelectrode patterns; and heating said second orientation film.
 16. Amethod according to claim 11, wherein said base film comprisespolyethylene terephthalate.
 17. A method according to claim 11, whereinsaid first and second substrates comprise a material selected from thegroup consisting of polyethylene terephthalate, polyethylene naphalate,polyethylene sulfite, polyimide, and polyarylate.
 18. A method accordingto claim 11, further comprising a step of fabricating nonlinear devicesand TFTs simultaneously by printing techniques.
 19. A method accordingto claim 11, wherein said overcoat film has a flattened surface.
 20. Amethod according to claim 11, wherein said display device is selectedfrom a passive matrix type display device and an active matrix typedisplay device.
 21. A method for fabricating display device comprisingsteps of: forming color filters on a front surface of a flexible basefilm; forming a protective film over said color filters; forming anadhesive film on a rear surface of said flexible base film; sticking afirst flexible substrate to said flexible base film with said adhesivefilm interposed therebetween; removing said protective film from saidfirst flexible substrate; forming a transparent resin film over saidcolor filters and said first flexible substrate; disposing anelectro-optical material over said resin film; bonding said firstflexible substrate to a second flexible substrate with saidelectro-optical material interposed therebetween to form a substrateassembly; and cutting said substrate assembly to form a plurality ofelectro-optical cells.
 22. A method according to claim 21 furthercomprising steps of: forming a first orientation film over said firstelectrodes pattern; heating said first orientation film; and rubbing asurface of said heated first orientation film.
 23. A method according toclaim 21 further comprising at least a step of forming a sealingmaterial over said first substrate.
 24. A method according to claim 21wherein said protective film and said adhesive film are stuck on bothsides of base film, respectively, using a pair of rolls.
 25. A methodaccording to claim 21 further comprising steps of: forming secondelectrode patterns over said second substrate; forming a secondorientation film over said second electrode patterns; and heating saidsecond orientation film.
 26. A method according to claim 21, whereinsaid base film comprises polyethylene terephthalate.
 27. A methodaccording to claim 21, wherein said first and second substrates comprisea material selected from the group consisting of polyethyleneterephthalate, polyethylene naphalate, polyethylene sulfite, polyimide,and polyarylate.
 28. A method according to claim 21, wherein saidelectrooptical material is a liquid crystal material.
 29. A methodaccording to claim 21, wherein said display device is selected from apassive matrix type display device and an active matrix type displaydevice.
 30. A method for fabricating a display device comprising stepsof: forming color filters on a front surface of a lengthy flexible basefilm; sticking a first lengthy flexible substrate on a rear surface ofsaid base film; forming first electrode patterns to over said firstsubstrate; disposing an electro-optical material over said firstelectrode patterns; sticking a second lengthy flexible substrate to saidfirst substrate to form a substrate assembly; and cutting said substrateassembly into a plurality of cells.
 31. A method according to claim 30further comprising a step of forming an overcoat film over said colorfilters.
 32. A method according to claim 30 wherein said base filmcomprises polyethylene terephthalate.
 33. A method according to claim 30wherein said first and second substrates comprise a material selectedfrom the group consisting of polyethylene terephthalate, polyethylenenaphalate, polyethylene sulfite, polyimide, and polyarylate.
 34. Amethod according to claim 30 wherein said display device is selectedfrom a passive matrix type display device and an active matrix typedisplay device.
 35. A method for fabricating a display device comprisingsteps of: forming color filters on a front surface of a lengthy flexiblebase film; sticking a first lengthy flexible substrate on a rear surfaceof said base film; forming an overcoat film over said color filters andsaid first substrate; forming first electrode patterns over saidovercoat film; forming second electrode patterns over a second lengthyflexible substrate sticking said second substrate to said firstsubstrate in order to form a substrate assembly; and cutting saidsubstrate assembly into a plurality of cells.
 36. A method according toclaim 35 wherein said overcoat film comprises transparent resin.
 37. Amethod according to claim 35 wherein said base film comprisespolyethylene terephthalate.
 38. A method, according to claim 35 whereinsaid first and second substrates comprise a material selected from thegroup consisting of polyethylene terephthalate, polyethylene naphalate,polyethylene sulfite, polyimide, and polyarylate.
 39. A method accordingto claim 35 further comprising a step of fabricating nonlinear devicesand TFTs simultaneously by printing techniques.
 40. A method accordingto claim 35 wherein said display device is selected from a passivematrix type display device and an active matrix type display device. 41.A method for fabricating a display device comprising steps of: drawing abase film out of a roll around which a base film is wound; forming colorfilters on a front surface of said base film; drawing a first substrateout of a roll around which said first substrate is wound; sticking saidfirst substrate on a rear surface of said base film having said colorfilters thereon; and forming first electrode patterns to over said firstsubstrate.
 42. A method according to claim 41 wherein said base filmcomprises polyethylene terephthalate.
 43. A method according to claim 41wherein said first substrate comprises a material selected from thegroup consisting of polyethylene terephthalate, polyethylene naphalate,polyethylene sulfite, polyimide, and polyarylate.
 44. A method accordingto claim 41 further comprising a step of fabricating nonlinear devicesand TFTs simultaneously by printing techniques.
 45. A method accordingto claim 41 wherein said display device is selected from a passivematrix type display device and an active matrix type display device. 46.A method for fabricating a display device comprising steps of: formingcolor filters on a front surface of a lengthily flexible base film;forming a protective film over said color filters; forming an adhesivefilm on a rear surface of said base film; sticking a first flexiblesubstrate to said base film with said adhesive film interposedtherebetween; removing said protective film from said first substrate;forming a transparent resin film over said color filters and said firstsubstrate; and disposing a liquid crystal material over said resin film.47. A method according to claim 46 wherein said protective film and saidadhesive film are stuck on both sides of base film, respectively.
 48. Amethod according to claim 46 wherein said base film comprisespolyethylene terephthalate.
 49. A method according to claim 46 whereinsaid first substrate comprises a material selected from the groupconsisting of polyethylene terephthalate, polyethylene naphalate,polyethylene sulfite, polyimide, and polyarylate.
 50. A method accordingto claim 46 wherein said display device is selected from a passivematrix type display device and an active matrix type display device.